Investigation On High Efficient Forming Of TC4 Titanium Alloy Fabricated By Wire And Arc Additive Manufacturing

Due to its excellent mechanical properties,titanium alloys are widely used in aviation,aerospace and other industries.However,their excellent mechanical properties such as high specific strength,high shear modulus and low thermal conductivity lead to difficulties in traditional machining methods,long machining cycles and high processing costs,low material utilization,it's difficult to meet the economic and rapid manufacturing requirements.Additive manufacturing technology with rapid manufacturing,high manufacturing capacity,high material utilization,can be widely used in manufacturing large-scale titanium alloy structure parts in aviation,aerospace and other industries.Therefore,in order to meet the future application of additive manufacturing technology in the manufacturing of large-scale titanium alloy structural parts,this paper mainly investigates the forming problem of wire and arc additive manufacturing,use Ti-6Al-4V titanium alloy as the forming material.First,aiming at the problem of forming anisotropy caused by the wire feeding method,the solution is proposed from two aspects of "wire feeding method" and "process parameters".Second,in order to realize the rapid manufacturing of large-scale titanium alloy structural parts,according to the theoretical calculation and experimental experience,the process parameters are optimized,the forming efficiency is improved by 77.8% while the heat input is reduced by 25%.Then the tool-path is optimized according to the microstructure and mechanical properties of fabricated samples.Finally using the optimized process parameters and tool-path to fabricate the extractor for trial production.The main conclusions of this paper are as follows:1.Coaxial wire feeding and point-by-point forming process can solve the forming anisotropy problem in wire additive manufacturing.Coaxial wire feed using laser beams as heat source,the fabricated samples have no forming anisotropy and have nearly the same mechanical properties in horizontal and vertical directions,while the point-by-point forming process without adding additional auxiliary equipment or control system,successfully solves the forming anisotropy in wire and arc additive manufacturing process,and trial sample verification.2.In the combination of theoretical formula and experimental experience,the high-efficiency isotropic forming process based on 1.6mm TC4 titanium alloy wire is proposed,which improves the forming efficiency by 77.8% compared with the original process.At the same time,by reducing the base current and increasing the scanning speed,reduced average heat input by 25%.3.The different forming tool-paths affect the forming quality and mechanical properties of the fabricated samples.The different lapping ways in the forming tool-path lead to different forming precision and mechanical properties of the fabricated samples.Although the lapping ways of the interlaminate lamellae can obtain better forming profile,the fabricated sample has low mechanical property.Continuous lap of the forming tool-path,get better mechanical properties of the fabricated sample,while leaving the allowance to ensure that the late machine smoothly.